Research On The On-Orbit Integrated Optical Load Support Technology

As China is gradually entering the era of the space station,the maintenance and integration of spacecraft in orbit has gradually become a more intensive,convenient and efficient technical means for solving space science research.The space load can be integrated in orbit,and the integration with the satellite platform can be completed by the astronaut or space robot in orbit,It is not subject to transportation restrictions,has a stable microgravity environment,and can accomplish many tasks that cannot be achieved in the ground environment.This is a promising direction for the future development of the aerospace industry,however,compared with the traditional space load development process,an on-orbit operation is added,under this working condition,there are a series of unprecedented problems such as low temperature and man-machine operation,especially relative to the optical load,the optical system is prone to aberrations under extremely severe thermal conditions,how to have better force and thermal environment stability will become the main research direction of the on-orbit integration optical load.In order to solve the problem of support technology that can integrate the optical load on the rail,this paper have designed a kinematic support scheme,and researched around the core issues of temperature adaptability and positioning accuracy of the support scheme.First of all,the main technical difficulties of this subject are analyzed and determined.This kind of load needs to have both high environmental adaptability and extremely high positioning accuracy,as well as good on-orbit man-machine operability,in order to solve the above contradictions of high adaptability,high positioning accuracy and high operability,this paper proposes a parallel support method that can integrate optical loads on the rail,using a combination of statically determinate kinematic support and a locking mechanism.The above contradiction was resolved,and the mechanism principle analysis and environmental adaptability analysis of the organization were laid,which laid the foundation for solving such problems.Secondly,for this supporting scheme,the temperature adaptability mechanism was studied.Combined with the principle of support mechanism,the layout of support points,the temperature difference between the load and the platform,the theoretical analysis of the influence of the load positioning accuracy was carried out,and the temperature change kinematic model was established.Combined with the model,the deformation was analyzed and calculated,the calculation results show that the device can effectively release the deformation caused by temperature change and realize the unloading of thermal stress,and the positioning accuracy of the load has a certain change rule with the temperature difference between the load and the platform.This rule has important guiding significance for the design of the layout of the support point,the selection of the support structure material,and the allocation of temperature control indicators.Next,the mechanism of the influence of the movement pair clearance and manufacturing error on the load positioning accuracy in this support method is analyzed.The movement pair clearance and manufacturing error of the supporting structure are the main factors affecting the load positioning accuracy.In this paper,the movement pair clearance and manufacturing error are equivalent to massless connecting rods,and the originally theoretically statically fixed support mechanism is equivalent to a multi-degree-of-freedom mechanism.Through the kinematics analysis of the equivalent mechanism,the influence of the clearance of each pair of motions and manufacturing errors on the accuracy of load positioning is obtained,on this basis,the error distribution method of each motion pair is proposed.This research is helpful to predict the relationship between the value of the gap between each pair of motions and the maximum possible positioning error,and provides a scientific and effective basis for the reasonable allocation of the gap between each motion pair and the manufacturing error.Then,the stress sensitivity of the supporting mechanism is analyzed.Considering that there is a large difference between the load development status on the ground and the on-orbit application status,the effect of loading uncertainty on the positioning accuracy of the kinematic pair is studied.In this paper,the Hertz theory method is used to complete the establishment of the physical model of the contact interface of the moving pair,the Lagrange method is used to establish the system dynamics equation,the relationship between the applied load and the positioning accuracy is established by this equation,the flexible sensitivity of the support mechanism and its material are derived,this theory has significant guiding significance for rational selection of design parameters and optimization of support structure design.Finally,the production of the principle prototype was completed,a test platform was built,a test plan was planned for the influence of the clearance and temperature of the motion pair,and the adaptability and positioning accuracy of the support mechanism were tested and verified by analysis and calculation.The test results show that the repeated positioning accuracy caused by the movement pair clearance is better than 0.02mm;the deformation law brought by temperature change is close to the analysis value.It proves that the design scheme proposed in this paper is reasonable and the analysis method is more accurate,which can effectively guide the design work of this type of support structure.